抚育间伐对侧柏人工林及林下植被生长的影响

抚育间伐是森林经营管理措施之一,是对森林生态系统的人为干扰。研究不同抚育方式、强度和频率对森林生态系统的干扰对重建、恢复森林生态系统固有功能及实现森林可持续经营管理有重要意义。以31块北京地区侧柏人工林样地对不同抚育强度后侧柏林生长、林下植被生长及林下植物多样性变化进行了研究。研究结果表明:侧柏林分经不同强度抚育后单木胸径、树高、冠幅和林分蓄积生长均增加,不同抚育强度下单木胸径、树高、冠幅生长量和林分蓄积生长量与立地条件有关,好的立地条件宜采取强度抚育,较差立地条件宜采取中弱度抚育;侧柏林分经弱度、中度抚育后林下植物种类增加,经强度抚育后减少;不同强度抚育后林下植物Simpson多样性指数和Shannon-Wiener多样性指数随时间增大,后者对抚育强度更为敏感;林下灌草生物量随抚育强度增大而增加,并随时间增加;侧柏人工林生态系统种间竞争程度与立地条件有关,好的立地条件能够经受较强的人为干扰,差的立地条件受弱度干扰就会打破种间生长平衡。

Effect of thinning on Platycladus orientalis plantation and the diversity of undergrowth vegetation

Thinning is one of the important methods of forest management and human disturbance to forest ecosystem. Researching on different thinning methods, intensity and frequency has an important significance for rebuilding and recovering the intrinsic function of forest ecosystem and achieving sustainable forest management. 31 Platycladus orientalis plantation stand plots were used for researching the arbor and under-vegetation growth variation and diversity. Results showed that different thinning intensity increasing the diameter, height, crown and stand volume growth. The amount of the growth indices after different thinning intensity related to the site type. Heavy thinning intensity could been fit for the high quantity site and the low or middle intensity fit for the low and middle quantity site. The amount of undergrowth vegetation species has an increasing trend after thinning with low and medium intension but decreasing after the heavy intension. The Simpson index and the Shannon-Wiener index became larger after thinning, and the value increasing throw time. The Shannon-Wiener index was more sensitive with the thinning intension. Biomass of the under-vegetation was increasing with the thinning intension and the time. Interspecific competition of Platycladus orientalis plantation ecosystem has a close relationship with site type. The better site could endured the heavily human disturbance and the growth balance would been easily broken by the disturbance in a worse site.